Ionic Currents: Lecture 10 Flashcards
What are the symptoms of Epilepsy
Generalised symptoms:
Repetitive seizures which can involve loss of consciousness or tonic clonic convulsions
Dependent on source:
Can lead to auras
What are the causitive reasons of epilepsy
Genetic causes lead to unpredictable syndromes
Neurological disturbance / trauma leads to aquired syndromes
How do you diagnose epilepsy?
Medical history
EEG recordings - measuring electrical activity with brain surface recordings- measure cortical neuron activity normally 1-30Hz
EEG spikes normally associated with over-activity
PET and MRI scans can be used to identify deep locations
Describe the causes and symptoms of idiopathetic epilepsy syndrome
Inherited mutations in sodium channels leading to febrile seizures (temperature associated) in childhood
This then develops into general epilepsy
Describe the cortical neuronal circuit and the effects mutations can have
Gain of function mutations (excitatory) leads to:
persistent current –> peristent depolarisation - frozen posture, tonic-clonic seizures, cell death
Loss of function mutations (inhibitiory)
Decreased sodium current –> less feedback inhibition –> hyper-excitability –> epilepsy
Both types of mutations lead to seizures
Describe how benign neonatal familial convulsion (BNFC) comes about
Inherited mutations in ACh sensitive potassium channels.
Genetic: two seperate genes on two seperate chromosomes
Expression of KCNQ2 and 3 genes –> expression of subunits –> M-current (regulates AP firing- by decreasing excitability during long trains of AP’s )
When mutations occur in these subunits –> reduction of M-current by 20-30% –> hyperexcitability
What are the symptoms of benign neonatal familial convulsion?
Reoccuring breif seizures. Start 4 days into life and end by 3 months
Increases the chances of developing epilepsy
Muscarinic ACh receptor activation –> increased excitability due to depression of M-current.
What are M currents
A current which regulates the excitabability of neurons during AP firing.
Produced by channels which are heteromultimers of KNQ2 and 3 subunits
How does the M-current work during depolarisation
How does the M-current work during GPCR stimulation
Inhibtion of M current which leads to sustained AP firing producing seizures.
What is multiple sclerosis caused by?
Multiple sclerosis is an autoimmune disease caused by axon demyelination.
The lack of myelin means that the action potential can travel backwards, as well as propagating forwards less far and slower.
What are the symptoms of mutliple sclerosis
Blurred Vision
Muscle Weakness
Muscle spasms
Loss of sensation
What are the risk factors associated with multiple sclerosis
Genetic (mainly women)
Environment as well
